Pumps



0. HOLM PUMPS July 12, 1955 Filed Nov. 16, 1953 .fm emon' 0770 Ha -M 57 I United States Patent ruurs Otto Helm, Hambnrg-Langenhorn, Germany, assigner to H. Maihair A. G., Hamburg, Germany Application November 1d, 1953, Serial No. 392,4tl7 Claims priority, application Germany December 2, H52 19 tllaims. (Cl. 103-448) The present invention relates to a pump for fluid substances such as a pump proper for liquids or a compressor for gases. More particularly the present invention relates to a pump having a chamber the volume of which is alternately increased and decreased, the fluid entering the chamber through one or more suction valves and leaving the same through one or more pressure valves.

Pumps of the kind described are known in the art in which a ring-shaped resilient body is arranged between the piston and a wall portion of the chamber.

It is an object of the present invention to improve the design of such pumps.

'it is another object of the present invention to render such pumps capable of conveying the fiuid against high pressure such as 190 atmospheres and more.

it is a further object of the present invention to render U the delivery rate of the sure to be overcome.

It is still another object of the present invention to render the resilient ring-shaped body capable of withstanding high stresses Without damage.

Other objects and advantages of the present invention will become apparent from the detailed description thereof given hereinafter with reference to the drawings.

A pump according to the present invention comprises in its broadest aspect a body forming a chamber having a wall portion shaped as a frustum of a cone, a'piston arranged for reciprocating motion in the chamber, the piston defining with the body a Working space arranged at the narrow end of the wall portion of the chamber, and having a wall portion shaped as a frustrum of a cone tapering toward the working space in the same direction as the wall portion of the chamber, and a ring-shaped resilient body arranged between the wall portions of the chamber and the piston, the resilient body undergoing deformation at the reciprocating motion of the piston in the chamber.

The present invention will now be described more in detail with reference to the accompanying drawings forming part of the specification and showing, by way of example, some embodiments of the present invention. In the drawings:

Fig. 1 is a sectional elevation present invention;

Figs. 2-4 show in sectional elevation some more embodiments of the present invention, respectively, some parts being omitted;

Figs. 5 and 6 show, respectively, part of another embodiment of the present invention in two different positions;

Figs. 7 and 8 show, respectively, merit in two diiferent positions;

Fig. 9 shows at a scale slightly enlarged in comparison with Fig. 1, a further embodiment of the present invention;

Fig. 10 is a sectional elevation of still another embodiment of the present invention, some parts being omitted; and

pump less dependent on the presof an embodiment of the a modified embodi- Fig. 11 shows the pump shown in Fig. 1 with some additional devices, some parts of Fig. 1 being omitted in Fig. 11.

Referring now to the drawings and first to Fig. 1, a body 10 forms a chamber 11 having a wall portion 12 shaped as a frustum of a cone. A piston 13 is arranged for reciprocating motion in the chamber 11 and defines with the body 10 a working space 14 arranged at the narrow end of the wall portion 12 of the chamber 11. The piston 13 has a wall portion 15 shaped as a frustum of a cone tapering toward the working space 14 in the same direction as the Wall portion 12 of the chamber 11. A ring-shaped resilient body 16 preferably consisting of natural or synthetic rubber, or the like, is arranged between the wall portions 12 and 15'. Preferably the resilient body 16 is connected to the wall portions 12 and 15 by vulcanizing so as to adhere to the same. The body 10 has two conduits 17 and 17' containing, respectively, spring-loaded inlet and outlet valves 18 and'18'.

The operation of this device is as follows:

The piston 13 is driven in direction of the double arrow 19 by means of a driving device (not shown) so that it carries out a reciprocatory motion in the chamber 11 of the body 10 which is limited by the elastic deformability of the resilient body 16. In consequence thereof the working space 14 increases and decreases alternately the volume thereof. When the piston 13 carries out the downward stroke the Working space 14 is increased in volume thus opening the inlet valve 18 and closing the outlet valve 18', whereas at the opposite movement of the piston 13 the working space 14 is decreased in volume and the inlet valve 18 is closed and the outlet valve 18 is opened. The resilient body 16 is limited by surfaces having the shape each of a hollow frustum of a cone having inner and outer wall portions tapering in the same direction toward the working space 14 and corresponding to the Wall portions 12 and 15 of the chamber 11 and the piston 13, respectively. In consequence thereof the resilient material of the ring-shaped body 16 is subjected to a swelling load comprising at the same time a thrust and a pressure. Experience has shown that resilient bodies deformed in this manner are not subject to destruction. During an upward movement of the piston 13 the annular gap between the latter and the wall portion 12 decreases in volume, the resilient body 16 being squeezed and undergoing a light swelling at the ends thereof so that the end faces of the resilient body 16 are not subject to tensions but to compressions, thus vastly increasing its time of life.

' The thickness of the wall of the resilient body is small in comparison to the mean diameter thereof and amounts preferably to less than 20% of the mean diameter. thermore the resilient body 16 has a length in the direction of motion of the piston 13 which is at least three times as large as the mean wall thickness of the ringshaped resilient body 16. If the pump is designed for very high pr ssure, the length of the resilient body 16 in the direction of motion of the piston 13 should be much larger. A pump satisfying those two conditions operates even against high pressure with a good conveying effect.

Referring now to Fig. 2 of the drawings, it will be understood that the wall portion 22 of the chamber 21 of the body 20 has a conicity defined'by is smaller than the conicity of the piston 23. the resilient body 26 to the wall portions 22 and 25 is improved so that, if desired, the resilient body 26 need not even be connected to the wall portions 22 and 25 by vulcanization. By making the angle a smaller than the angle ,6 the pressing out of the resilient material of the body 26 by the excess pressure within the working space 24 is rendered more difficult. Preferably the difference between the angles {3 and on is made so large that parallel cross-sections being at right angles to theaxis AB of the piston 23 intersect the resilient body 26 in circular rings the Width of which decreases continuously as the distance thereof from the working space 24 increases. If this condition is satisfied the resilient body 26 will not be squeezed out of its position by the pressure of the pump so that, as mentioned hreinabove, the resilient body 26 need not'be connected by vulcanization to the body 20 and the piston 23, respectively.

Referring now to Fig. 3 of the drawings, an embodi:

' ment of the present invention is shown in which the body;30 is provided with a cylindrical chamber 300 arranged between the working space 34 and the conical wall portion 32 of the chamber 31. The resilient body has a disc-shaped portion 360 being in one piece with the same and filling the cylindrical chamber 300 so as to have a larger diameter than the conical end 32 of the, chamber 31 turning toward. the working space 34. Thus the disc 360 protrude with its edge portion 362 beyond the conical end 32 of the chamber 31 so as to form a continuation of. the piston 33 being the effective part thereof.

In the further modification shown in Fig. 4 of the drawings the disc-shaped portion 460 of the resilient body 46 is provided at the side turning toward the working space 44 with a resilient diaphragm 464 consisting preferably of a material being different from the material of the disc'shaped portion 460 and protecting the same against attacks by the liquids or gases present in the working space 44. For instance the diaphragm 464 may consist of metal and may be either smooth or corrugated. The diaphragm 464 may, if desired, consist of a material which may be connected to the disc-shaped portion 460 by vulcanizing or by a cement so as to adhere rigidly to the same. 7

It is to be understood, that the embodiments shown in Figs. 2-4 are provided with conduits and valves (not shown) similar to the conduits 17, 17' and the inlet and outlet valves 18, 18' shown in Fig. l.

' The quantities of fluid supplied and/or sucked in by a pump are largely dependent on the volume of the space remaining .at the end of the pressure stroke. In the embodiments shown in Figs. 58 the Working space is so shaped that it is practically completely reduced to zero volume at the end of the pressure stroke. In these embodiments of the present invention the body consists of two parts 510 and 511 and 710 and 711, respectively. In the embodiment shown in Figs. 5 and 6 the part 510 is provided with a recess 513 forming together with the end face of the piston 53 and the resilient body 56 the working space 54. 'As clearly shown in Fig. 6, at the end of the pressure stroke the piston 53 and the deformed resilient body' 56 follow with minimum play the contour of the working space which is thus reduced practically to zero volume. The embodiment shown in Figs. 7 and 8 differs from that shown in Figs. 5 and 6 by the shape of the part 710 which' is devoid of a recess such as the recess 513shown in Fig. 5. instead the piston 73 has in the end position shown in Fig. 7 a position in which its end face 732 is at a slight distance from the plane end face 722 of the part 710 so as to form therewith a working space 74 which is reduced to zero volume in the other end position of the piston 73 shown in Fig. 8.

The pump principle described hereinabove can be applied in pumps for injecting the fuel into diesel engines or Otto engines. In such engines it is desirable that after emptying the pump automatically sucks in the fuel and comes into operation if the fuel tank is arranged at a lower level than the pump, or by inadvertence the fuel has not been replenished in time. With the pumps v arrow 1180 the stroke of, and thus the quantity of'fluid,

1 in a body 1110. A driving 4 hitherto known always the pressure screw has to be unscrewed for this purpose so as to ventilate the pump and to cause it to operate again. With the design described hereinabove, however, an automatic sucking-in of fuel even from tanks arranged at a lower level than the pump can be accomplished by the construction shown in Fig. 9 of the drawings. As will be seen from this figure the pressure or outlet valve 920 of the pump is provided with a stem 918 extending into the working space 94 of the pump so that it collides with the piston 93 shortly before the end of the pressure stroke thereof, thereby opening the valve 020 against the action of resilient means such as a valve spring 922 urging the valve 320 into the closed position thereof. This enables the air contained in the working space 94 to escape through the pressure valve 920 connected therewith. A further advantage of this design consists in that the piston 93 when it starts the return motion sucks back some fuel from the pressure connection upper face of the returning piston 93. In consequence thereof the pressure in the connection 930 is eased and the end of the injection is more markedly defined.

Referring now to Fig. 10 of the drawings, the pump has a body consisting of two parts 1010 and 1011. The part 1010 is substantially cylindrical and has a boring on one end thereof accommodating the piston 1003, the resilient body 1016, and the working space 1014. The part 1011 is cylindrically shaped and has a step 1030 conmeeting its upper portion 1032 fitting exactly in diameter the cylindrical part 1010,,with its lower portion 1034 having a slightly smaller diameter. A stop member such as a ring 1040 is placed below the part 1010 of the body and the resilient body 1016, and imparts to the latter a preliminary tension so as to keep the latter from taking the untensioned shape indicated by dotted lines. Therefore the resilient body 1016 is pre-tensioned and thus will drive the piston 1003 of the p'umpsimilar to a resilient spring known in the, art which drives the pump while the ring 1040 prevents the untensioning of the pre-tensioned resilient body 1016 so as to obtain a course of the injection which is predetermined with respect to time.

The amount of fluid conveyed per unit time by the pump can be changed during operation by any of the methods'usual with fuel feeding pumps, including the control of the conveying stroke by means of adjustable cams, the control of the back flow by means of. a controlled valve, or the pressure control by means of an automatic back flow valve having a variable spring load. Referring now to Fig. 11 of the drawing, a device is shown for controlling the stroke which is particularly suitable for fuel pumps of Diesel engines. The piston 1103 is connected by a resilient body 1106 with the frustoconical wall portion 1117 of the chamber 1111 formed eccentric 1144 is surrounded by a loose ring 1142 connected with the piston 1103 by an intermediate member generally denoted by 1130 and consisting of a sliding'member 1140 arranged for reciprocating motion in a recess 1146 ofthe body 1110, a pressure member 1150 and a helical compression spring 1160 inserted with pre-tension between the'pressure member 1150 and the disc 1170 arranged at the lower end of the shaft 1172 of the piston 1103. Theshaft 1172 has a frusto-conical boring 1174 in which the frusto-conical part 1176 of a bolt 1178 can be adjusted in the direction of the double arrow 1180. The positionof the bolt 1178 shown in Fig. 11 is the left end position in which the frusto-conical part 1176 thereof is in contact with the frusto-conical boring 1174 of the shaft 1172, the stroke of the piston 1103 being reduced to zero.

By displacing the bolt 1178 in direction of the double conveyed by, the pump can be adjusted. The stroke of the driving eccentric 1144 and thus that of the pressure member 11 50 is constant. As long asthe conveying 930 since the valve 920 is t 'I still open because the stem 918 is in contact with the pressure of the pump does not exceed a predetermined value the bolt 1178 is in its right end position (not shown) and allows the pre-tensioned compression spring 1160 which carries along the sliding member 1140, to transfer the motion thereof to the shaft 1172 of the piston 1103. However, when the bolt 1178 is adjusted so that the frusto-conical part 1176 thereof is in a different position with respect to the boring 1174, the stroke of the piston 1103 is limited because the movement of the shaft 1172 is limited by the contact the frusto-conical part 1176 of the bolt 1178, the compression spring 1160 being shortened during part of the stroke of the pressure member 1150.

It should be noted that by this method of control the end of the conveying action is rendered variable so that the pump can be used as a fuel pump for Diesel engines. The spring 1169 constitutes a safety member against the clogging (if any) of the injection nozzle.

Instead of the conical bolt 1178 a Wedge or an eccentric or any other adjustable stop the adjustment of the stop member is effected in the non-load intervals intercalated between consecutive strokes of the pump, the frictional resistance to be overcome during the adjusting operation is very small so that only a small force is the adjusting device need only be small. The angle of inclination of the bolt should be smaller than the angle of friction so that it is self-locking and does not exert a back pressure on the adjusting device.

Furthermore, the resilient member intercalated in the driving device has the effect of limiting the pressure increase in the connection between the pump and the injection nozzle, and in the pump itself, and of lengthening the time of the injection at a high number of revolutions in connection with open injection nozzles so that at a thorough atomization with nozzle openings remaining equal, a larger range of numbers of revolutions per minute is coverable.

It should be understood that numerous changes may be made in the form, construction and arrangement of the several parts of the illustrated pump without departing from the spirit and scope of my invention or sacrificing any of its advantages, the forms herein described being merely for the purpose of illustrating the invention.

What I claim and wish to secure by Letters Patent is:

1. In a pump, comprising, in combination: a body forming a chamber having a wall portion shaped as a frustum of a cone, a piston arranged for reciprocating motion in said chamber, said piston defining with said body a working space arranged at the narrow end of said wall portion of said chamber, and having a wall portion shaped as a frustum of a cone tapering toward said working space in the same direction as said wall portion of said chamber, and a ring-shaped resilient body arranged between said wall portions of said chamber and said piston, said resilient body undergoing deformations at the reciprocating motion of said piston in said chamber.

2. In a pump, comprising, in combination: a body forming a chamber having a wall portion shaped as a frustrum of a cone, a piston arranged for reciprocating motion in said chamber, said piston defining with said body a working space arranged at the narrow end of said wall portion of said chamber, and having a wall portion shaped as a frustum of a cone tapering toward said working space in the same direction as said wall portion of said chamber, and a ring-shaped resilient body arranged between said wall portions of said chamber and said piston and adhering to the same, said resilient body undergoing deformations at the reciprocating motion of said piston in said chamber.

3. In a pump, comprising, in combination: a body forming a chamber having a wall portion shaped as a frustum of a cone, a piston arranged for reciprocating motion in said chamber, said piston defining with said body a working space arranged at the narrow end of said of the boring 1174 thereof with member may be used. Since a.

needed for the adjustment and thus wall portion of said chamber, and having a Wall portion shaped as a frustum of a cone tapering toward said working space in the same direction as said wall portion of said chamber, said wall portion of said piston having a vertex angle larger than the vertex angle of said wall portion of said chamber, and a ringshaped resilient body arranged between said wall portions of said chamber and said piston, said resilient body having cross-sections in planes vertical to the direction of motion of said piston, said cross-sections decreasing continuously as the distance thereof from said working space increases, said resilient body undergoing deformations at the reciprocating motion of said piston in said chamber.

4. In a pump as claimed in claim 1, said ring-shaped resilient body having a wall thickness being small in comparison to the mean diameter of said ring-shaped resilient body.

5. In a pump as claimed in claim 1, said ring-shaped resilient body having a wall thickness being less than 20 percent of the mean diameter of said ring-shaped resilient body.

6. In a pump as claimed in claim 5, said ring-shaped resilient body having a length in the direction of motion of said piston being at least three times as large as the mean wall thickness of said ring-shaped resilient body.

7. In a pump, comprising, in combination: a body forming a chamber having a wall portion shaped as a frustum of a cone, a piston arranged for reciprocating motion in said chamber, said piston defining with said body a working space arranged at the narrow end of said wall portion of said chamber, and having a wall portion shaped as a frustum of a cone tapering toward said working space in the same direction as said wall portion of said chamber, a ring-shaped resilient body arranged between said wall portions of said chamber and said piston, said resilient body undergoing deformations at the reciprocating motion of said piston in said chamber, and a disc consisting of the same resilient material as said ringshaped body and forming one piece therewith, said disc being arranged at the side of said ring-shaped body turning toward said working space.

8. In a pump as claimed in claim 7, a substantially cylindrical space forming the intermediary between said working space and said portion of said chamber, said cylindrical space having a larger diameter than the end of said portion of said chamber turning toward said working space, said resilient dics having a diameter substantially equal to the diameter of said cylindrical space and being arranged therein so as to protrude with the edge portion thereof beyond said end of said portion of said chamber turning toward said working space.

9. In a pump as claimed in claim 8, and arranged on the side of said disc turning working space, said diaphragm separating said disc from said working space.

10. In a pump as claimed in claim 9, said diaphragm consisting of a resilient material being different from the material of said disc.

11. In a pump as claimed adhering rigidly to said disc.

12. In a pump as claimed in claim 1, said working space being so shaped that at the end of the pressure stroke said piston and said deformed resilient body substantially follow the contour of said working space.

13. In a pump as claimed in claim 1, said working space being so shaped that at the end of the pressure stroke said piston and said deformed resilient body follow the contour of said working space with minimum play.

14. In a pump as claimed in claim 1, an inlet valve and an outlet valve connected to said working space, and means for opening said outlet valve shortly before the end of the pressure stroke of said piston.

15. In a pump as claimed in claim 1, means defining a valve chamber connected to said working space, an

a diaphragm toward said said side of in claim 10, said diaphragm driving means and said piston,

7 inlet valve and an outlet valvev arranged in saidrvalve chamber, resilient means urging said valves into the closed position thereof, and an extension rigidly connected with said outlet valve and protruding into said working space so as to collide with said piston shortly before the end .of the pressure stroke thereof.

16. In a pump as claimed in claim 1, driving means for said piston, and resilient member arranged between said said resilient member forming, up to a predetermined load, a rigid connecting member between said driving means and said piston, said resilient member shortening the length thereof when the load is larger than said predetermined load.

. 17. In a pump as claimed in claim 16, and means for arbitrarily limiting the motion of said resilient member so as to change the amount of fluid conveyed by the pump while the remaining part of the stroke of said driving means is absorbed by the elastic deformation of said resilient member.

18.'In a pump as claimed in claim 1, and means for imparting a p reliminary tension to said resilient body,

said preliminary tension of said resilient body being in opposition to the force exerted by the fluid conveyed by the pump, said preliminary tension urging said resilient body into a position increasing said working space.

19. In a pump asrclaimed in claim 18, said imparting means being formed as a 'stop member arranged across the end of said ring-shaped resilient body turned away from said working space, said stop member limiting during a suction stroke the motion of said piston.

References Cited in the file of this patent UNITED STATES PATENTS 

